On 2014/2/11 18:20, Michal Hocko wrote: > Hi Li, > good work in reproducing the issue so quickly! > I have tried to backport this patch to 3.12 kernel but the code has > changed since then. > The only two instances of idr_remove which are called outside of > cgroup_mutex seem to be: > - cgroup_create calling it from err_free_id: path > - css_free_work_fn > mem_cgroup_css_free > __mem_cgroup_free > free_css_id > > The second one takes ss->id_lock spinlock which should be sufficient > to exclude get_new_cssid but cgroup_mount and cgroup_create don't use > id_lock. They do hold cgroup_mutex though. So I guess I need something > like the following (I will have it tested): I don't think you need to do anything with ss->idr. cgroup_create() calls alloc_css_id() -> get_new_cssid(), and get_new_cssid() uses id_lock. cgroup_mount() won't touch ss->idr, because the css_id for root cgroup is always 0. -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
